The invention is based on an electric motor-and-gear assembly for driving vehicle aggregates such as windshield and rear window wipers, power-window units and the like.
A known motor-and-gear assembly for power-window units in motor vehicles (DE 90 13 006 U1) has a transmission housing which adjoins the commutator end of the commutator motor and into which the elongated motor shaft protrudes as a transmission drive shaft (worm shaft). A printed circuit board is disposed in an electronic housing and is electrically connected to an external connector plug and commutator brushes as well as components of a set of motor electronics. The printed circuit board has a one-piece receiving part for the brush holder and a one-piece receiving part for the connector plug. The electrical connections of the components, the commutator brushes, and the connector plug are contacted by the strip conductors of the printed circuit board. The commutator brushes are disposed diametrically opposed on the commutator and are respectively held so that they can move radially in a tubular brush holder embodied in the brush holder. The electronic housing is a component of the transmission housing and is closed by an electronic housing cover that is of one piece with the transmission housing.
The electric motor-and-gear assembly according to the invention for driving vehicle aggregates has the advantage that the embodiment of the brush carrier as a U-shaped carrying piece on the one hand and the embodiment of the commutator brushes as so-called hammer brushes on the other hand assures an inexpensive manufacture of the brush holder and a time-saving, simple assembly since after the motor-and-gear assembly has been completely assembled, the brush holder can be slid radially over the commutator through the housing opening in the transmission housing in a single work cycle and is thereby positioned in the transmission housing in a highly precise manner. No other manipulations or adjusting measures are required. Since the hammer brushes are affixed to the brush holder, their sliding bodies, also called carbon strips, also rest in a precise position on the circumference of the commutator after the insertion of the brush holder. When the transmission is closed by means of the transmission cover, the brush holder is securely fixed without additional steps.
The hammer brushes have the advantage that the spring steel sheets have a very favorable ability to dissipate heat from the sliding bodies and therefore the carrying part itself does not have to assume any heat-dissipating function so that the carrying part can be inexpensively made of plastic. The manufacture of the carrying part of plastic makes it possible, through the injection molding of additional pockets onto the carrying part, for components for the motor electronics, such as thermal circuit breakers, interference suppression elements (capacitor, throttle), to be inserted into the brush holder itself and therefore permits a simplified assembly after a prior assembly of the brush holder.
Advantageous improvements and updates of the electric motor-and-gear assembly are possible by means of the measures set forth hereinafter.
According to a preferred embodiment of the invention, at least one elastomer element is disposed between the underside of the carrying part oriented toward the transmission cover and the inside of the transmission cover. This elastomer element is preferably part of a seal, which is injection molded onto the transmission cover and is made, for example, of rubber-like material. These measures achieve an extensive decoupling of the brush holder from the transmission cover, which is also made of plastic, and thus achieves a noise reduction.
According to an advantageous embodiment of the invention, assembly aids for sliding the brush holder onto the commutator are embodied on the free ends of the spring leaf actuators of the hammer brushes. These assembly aids, which are preferably embodied as projections with insertion bevels and are inclined toward the outside from the end of the spring leaf actuators, make it significantly easier to slide the hammer brushes onto the commutator and the assembly of the brush holder can be executed without auxiliary tools.
According to an advantageous embodiment of the invention, the pigtails for the hammer brushes are fixed in clamping forks embodied on the carrying part, preferably of one piece with the carrying part. This achieves an assembly-facilitating fixing of the pigtails which is imperative for a noise reduction and increased service life of the motor.